Alzheimer's disease is the most common brain disease which has huge social and economical burdens for the modern society. It is caused by accumulation of the toxic peptides, called amyloid beta, in the brain. There is no treatment for this devastated condition. We have identified a fragment of antibody specifically recognizing amyloid beta peptides which dissolves and remove the plaques from the brain. This project is to further test this novel drug in mouse model of the disease.